Field
The teachings in accordance with the exemplary embodiments of this present disclosure generally relate to an apparatus for determining start of electric machine.
Background
In general, 3-phase motors such as induction motors and synchronous machines are differentiated in operation methods when with a position sensor and when without a position sensor.
The position sensor such as an encoder and a resolver is frequently used to measure a position and a speed of a rotor, but use of the position sensor disadvantageously increases costs of an entire system, maintenance costs and the volume of the entire system in addition to being weak to fault. In order to overcome these disadvantages, the industries require a demand on sensor-less operation of a 3-phase motor free from a position sensor. However, conventional sensor-less operation of 3-phase motor suffers from failure to determine start of the motor after start of sensor-less operation, which is generated by an error between rotor speed and position estimation.
Particularly, it is difficult to precisely grasp an operation state of a motor in terms of rotor speed and position estimation at a lower speed region of the rotor, making it difficult to determine whether the motor has started successfully.